1. Field of the Invention
This invention relates to electrical lighting and, more particularly, to apparatus and method providing shatter-resistant electric lamps.
2. Description of the Prior Art
Electric lamps of many varieties are well known, such as incandescent lamps, vapor lamps (sodium vapor lamps, mercury vapor lamps, etc.), arc lamps, fluorescent lamps, ultraviolet lamps, etc. These electric lamps typically have at least one base which provides structural support for the lamp and which also provides positive, negative, and grounding contacts for electrical power. A filament, or light source, which converts electrical energy to light is connected between the contacts. The filament is generally encased in a translucent encasement which protects the filament from the surrounding environment and contains the gaseous vapors, vacuum, etc. surrounding the filament and needed for the electric lamp to operate properly. The encasement is usually a translucent glass container, such as a light bulb.
Electric lamps, particularly the larger sizes, can be very expensive. The cost of such lamps is increased in lamps which operate at high temperatures, e.g., high intensity incandescent lamps such as flood lamps. In order to withstand high temperatures and provide a relatively long life, the lamp components must be made of temperature resistant materials which many times are more expensive. For example, the glass encasement is generally made heavier or thicker to withstand higher temperatures. If the lamp is to be used outdoors, the glass must be able to withstand the outdoor temperature fluctuations, as well as the stresses created when the hot lamp is exposed to cooler rain showers, wind gusts, etc.
Since glass will break or shatter, and in many types of electric lamps the glass bulb is not replaceable, i.e., if the glass bulb breaks, the entire lamp must be replaced, the glass bulb is many times made heavier than necessary to reduce the possibility of breakage. This heavier glass also increases the costs of the electric lamp.
The present invention is directed to apparatus and method which prevent or reduce the breakage of electric lamps.